A prebiotic nanofibre matrix that protects beneficial bacteria in the low pH environment of fruit juices could prove an effective encapsulation agent for the probiotic delivery in functional beverages.

The material--composed of 50% pectin, 25% nanochitin and 25% nanolignocellulose—provided protection for the probiotic Bacillus coagulans​ cells when mixed with peach juice at a pH of 3.6 over 5-week storage period at both 4°C and 25°C, according to Polish scientists.

The findings could well be of interest to the probiotic food industry, which has seen interest in probiotic-containing fruit juices, soya-based and confectionary products, fuel a global market worth €147.6bn ($176.7bn) in 2013.

Despite their popularity, the low pH environment of some fruit juices continues to be a challenge for beverage manufacturers, who have turned to microencapsulation in order to maintain a sufficient number of viable probiotics in the product.

Among the used for this process, pectin is preferred due to its non-toxic, biocompatible and inexpensive properties.

In addition, chitin as a biocompatible and nontoxic polymer aids delivery systems in passing through the gastrointestinal tract.

Cellulose as a renewable biopolymer and the most abundant renewable resource has demonstrated probiotic protection against harsh gastrointestinal conditions by its inclusion into a pectin matrix.

Study details ​

In a collaboration between Iran’s Tarbiat Modares University and National Elites Foundation of Iran, the team began by using a mixture design method to blend pectin-based bionanocomposites with various compositions of nanochitin, nanolignocellulose and bacterial nanocellulose.

These were fabricated based on cross-linking of calcium ions with pectin for entrapment of the Bacillus coagulans​ probiotic.

The pH of the juice and synbiotic juice were measured in the beginning and at week 1, 2, 3, 4 and 5 during storage at 4°C and 25°C.

The survivability of microencapsulated B. coagulans​ incorporated into peach juice was also measured at the same time.

The survivability of the probiotic was also evaluated at 4°C and 25°C over a 5-week storage in peach juice and under simulated gastrointestinal conditions.

Study findings ​

Findings revealed that the survivability of B. coagulans ​entrapped within the pectin-nanochitin-nanolignocellulose matrix was approximately 65% under gastrointestinal treatment.

The maximum percentage survivability of the entrapped bacteria was approximately 68% compared to the survivability of the free cell (53%) at the end of 5-week storage period.

After the 21-day storage in the juice, the survivability of the entrapped bacteria treated under sequential digestion was approximately 58% as compared to that of the free cell (around 43%).

“One of the most important challenges for commercial probiotic products is probiotic fermentation that may lead to important product losses,”​ the study commented.

“The results of this study addressed the prebiotic bionanocomposite isolating the probiotic from the juice environment to inhibit the fermentation of sugars. Thus, the food quality of peach juices containing the microencapsulated probiotic can remained constant.​

The team also found the water-insolubility of the nanofibres caused resistance in the microencapsulation matrix to degradation under gastrointestinal digestion and during storage in peach juice - a feature attributed to its three-dimensional arrangement of the nanofibres of chitin and lignocellulose incorporated within pectin.

This structure contributed to a "uniform, relatively smooth coherent, compact and wrinkled morphology that was devoid of pores and cracks."​